We've got two numbers: 803 and 8156. Let's find their sum.

Step 1: We'll start by adding the digits 3 & 6 in column 1 and get 9.

Step 2: We'll start by adding the digits 0 & 5 in column 2 and get 5.

Step 3: We'll start by adding the digits 8 & 1 in column 3 and get 9.

Step 4: We'll start by adding the digits 0 & 8 in column 4 and get 8.

So, 803 + 8156 = 8959.

